Darwin 2.0: LSU Scientists Shed New Light on How Species Diverge

11/20/2014 04:07 PM

BATON ROUGE – Birds that are related, such as Darwin’s finches, but that vary in beak
size and behavior specially evolved to their habitat are examples of a process called
speciation. It has long been thought that dramatic changes in a landscape like the
formation of the Andes Mountain range or the Amazon River is the main driver that
initiates species to diverge. However, a recent study shows that speciation occurred
much later than these dramatic geographical changes. Researchers from LSU’s Museum
of Natural Science have found that time and a species’ ability to move play greater
parts in the process of speciation. This research was published today in the print
edition of Nature.

“The extraordinary diversity of birds in South America is usually attributed to big
changes in the landscape over geological time, but our study suggests that prolonged
periods of landscape stability are more important,” said Robb Brumfield, LSU Museum
of Natural Science director and Roy Paul Daniels professor in the Department of Biological
Sciences, one of the lead authors.Brumfield and his colleagues examined the genealogy of 27 species of birds in the
most bio-diverse region in the world, the Neotropics, which extends from southern
Mexico through Central America to southern Brazil and includes the Amazon rainforest.

“By using detailed sampling of many bird lineages, we were able to get a clearer and
larger picture of when and how species formed within those lineages,” Brumfield said.

The genetic data showed multiple accounts of species divergence, from nine to 29 different
instances across the Andes Mountains that varied over time. This shows that rather
than being the primary cause of speciation, the formation of the Andes Mountains had
an indirect effect on diversification as a semi-permeable barrier.

The researchers then investigated how the history and ecology affected speciation
among the 27 lineages of birds. They discovered the longer length of time a species
can inhabit an area, the more likely it will disperse and diverge. Also, the less
mobility a species has, the more likely it will diverge as well. For example, birds
restricted to the forest floor showed significantly higher species diversity than
birds that inhabited the forest’s open canopy. These findings have conservation ramifications.
If a species cannot inhabit the same area for an extended time, it will not have the
opportunity to evolve and continue.

This research was funded by the National Science Foundation. Other institutions involved
in this research include the American Museum of Natural History, City College of New
York, Museu Paraense Emílio Goeldi in Brazil, Universidad de los Andes in Colombia,
Universidad Central de Venezuela, Colección Ornithológica Phelps, University of California
Los Angeles and the University of Georgia Athens.

The thousands of samples used in this study represent the culmination of more than
30 years of field expeditions led by generations of LSU students and scientists, plus
similar work done by ornithologists at other research institutions.

The mission of the LSU Museum of Natural Science is the acquisition, preservation
and study of research collections by museum faculty, staff and students to generate
knowledge of regional and global biodiversity, geological history and human history/prehistory
for the benefit of the people of Louisiana, the nation and the world. For more information
on the museum, visit www.museum.lsu.edu. Follow the museum’s Twitter, @LSU_MNS. Like the museum’s LSU Big Day Peru Facebook
for updates as the international award-winning birding team prepares to break the
world Big Day record, www.facebook.com/LSUBigDay.

The mission of the Department of Biological Sciences is to create and disseminate
new knowledge in the biological sciences through research; to provide for its majors
the highest quality, nationally recognized, graduate and undergraduate educational
programs; to provide exceptional science training to support the university’s general
education requirements; and to contribute expertise in support of science education
in the community, including the use of available resources to improve K-12 science
outreach. For more information, visit www.biology.lsu.edu.